SAN ANTONIO — Manu Ginobili scored 26 points and the San Antonio Spurs won their 19th in a row to tie the NBA record for longest winning streak kept alive in the playoffs, beating the Oklahoma City Thunder, 101-98, to open the Western Conference finals on Sunday night.

Obeying orders snarled by coach Gregg Popovich in a fourth-quarter timeout to play “nasty,” the Spurs erased a nine-point deficit that stunned the Thunder, who had looked on their way to finally kicking the perception that they’re the underdog.

Kevin Durant led the Thunder with 27 points. Russell Westbrook had 17.

The 2001 Lakers are the only other team to carry a winning streak this long in the playoffs — and they did so on their way to a championship.

The Spurs matched the fourth-longest streak in NBA history, and with one more will become just the fourth team to surpass 20.

Tim Duncan had 16 points and 11 rebounds, and Tony Parker shook off a dismal start to finish with 18 points. But it was Ginobili who steered the Spurs to strike first in a highly anticipated matchup of the West’s top two teams for practically the entire regular season.

“They got us on our heels. We were not aggressive,” Ginobili said. “And in the second half, we did have it.”

On the other end, Oklahoma City’s own Big Three struggled to find its shot early before awakening in the second half. Yet Westbrook still finished just 6 of 15 and took a nasty, face-first spill late in the fourth that had the entire Thunder bench crossing the court to check on their All-Star point guard underneath the opposite basket.

Westbrook appeared to favor his left leg when he got up, but he never left the game.

It was a tantalizingly close near-upset for the young Thunder, who were ousted in the Western Conference finals a year ago and were in position for home-court advantage throughout the playoffs until being overtaken by the Spurs in the final month of the season.

But it was a fittingly close opener for two franchises with so many similarities.

That includes Thunder general manager Sam Presti — the architect of the Thunder’s rapid turnaround from a 23-win season to consecutive Western Conference finals in just four years — getting his big break in the NBA as intern in San Antonio.

And the Thunder didn’t even need their own Big Three to keep things close.

Durant, Westbrook and Harden at one point through the second quarter were 5 of 21 — a typically ominous stat line for a trio that had been responsible for nearly 70 percent of Oklahoma City’s points through the playoffs so far. But for all the talk about San Antonio’s superior bench, it was the Thunder’s reserves who picked up the slack.

None more so than Derek Fisher, whose famous game-winner for the Lakers on this same court in the 2004 playoffs has made “0.4 seconds” a phrase that needs no further explanation to the Spurs. Eight years later, and the oldest player in this series at 37, Fisher already met his playoff average at halftime and finished with 13 points.

Gary Neal added 12 points and was the only other Spurs player in double figures.